21433620209 has 4 divisors (see below), whose sum is σ = 21434066916. Its totient is φ = 21433173504.

The previous prime is 21433620199. The next prime is 21433620217. The reversal of 21433620209 is 90202633412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1005207025 + 20428413184 = 31705^2 + 142928^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21433620209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21433620269) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 141344 + ... + 250689.

It is an arithmetic number, because the mean of its divisors is an integer number (5358516729).

Almost surely, 2^21433620209 is an apocalyptic number.

It is an amenable number.

21433620209 is a deficient number, since it is larger than the sum of its proper divisors (446707).

21433620209 is an equidigital number, since it uses as much as digits as its factorization.

21433620209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 446706.

The product of its (nonzero) digits is 15552, while the sum is 32.

The spelling of 21433620209 in words is "twenty-one billion, four hundred thirty-three million, six hundred twenty thousand, two hundred nine".